What kind of air supply is connected to the breathing air system in aerial devices?

The correct answer is that the breathing air system in aerial devices is connected to compressed breathing air cylinders. This system is designed to provide firefighters with a safe and breathable air supply while they operate in hazardous conditions where the atmosphere may be contaminated or oxygen-deficient.

Compressed breathing air cylinders are specifically designed for use in respiratory protection systems. They ensure that the air supplied is clean, breathable, and free from harmful substances, as opposed to natural air from the environment, which can contain smoke and toxic gases during a fire. These cylinders allow for controlled and portable airflow to firefighters, making them essential for safety during aerial operations.

In contrast, portable air tanks carried by responders can be used in certain situations but generally are not the main air supply for aerial devices. The apparatus' engine system, while being a source of power for the equipment, does not supply breathable air.